There is always a need for photographing or mapping manmade or geographic features for use in determining distances or simply for recognition. Wide angle photographs taken of complex features, however, record features differently, depending on the position and angle of the camera. The relative positions of important features recorded by the camera film depend on perspective and the distance of those features from a plane perpendicular to the camera line-of-sight, as well as their distance measured along that plane. To avoid this problem, high-altitude photography, for example, may require very many narrow angle photographs taken of terrain directly beneath the camera. Mapping may utilize sterographic recording where two cameras are separated so as to afford the mapper the parallax he needs to determine the position of a feature which would occur on an orthographic projection. Both these techniques are tedious and time-consuming.
Therefore, it is an object of this invention to provide a system or process which utilizes only two photographs as an input and does not require a person to be involved in point-by-point transformation to an orthographic projection image.
Another object of this invention is to provide an orthographic projection which is not only of interest in mapping, but also is relevant to incoherent light image recognition for missile guidance.
Still another object of this invention is to provide a process or system for which, despite the change in size and perspective of images on the image plane, an on-course missile will always have a portion of the terrain/target image coincident with that of the orthographic projection on some suitable plane.
Other objects and advantages of this invention will be obvious to those skilled in this art.